Polymer/clay intercalates, exfoliates; and nanocomposites having improved gas permeability comprising a clay material with a mixture of two or more organic cations and a process for preparing same

ABSTRACT

This invention relates to a polymer-clay nanocomposite having an improved gas permeability comprising (i) a melt-processible matrix polymer, and incorporated therein (ii) a layered clay material intercalated with a mixture of at least two organic cations. The invention also relates to processes for preparing a nanocomposite and articles produced from a nanocomposite.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. provisional patent applicationSer. No. 60/111,199, filed Dec. 7, 1998, which is incorporated herein bythis reference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to polymer-clay nanocomposites havingimproved gas permeability comprising a clay material intercalated with amixture of organic cations and a polymer. This invention further relatesto intercalates, exfoliates, nanocomposites, and articles produced fromthe intercalates, exfoliates, and nanocomposites; and processes forpreparing the intercalates, exfoliates and nanocomposites, and articles.

BACKGROUND OF THE INVENTION

There is much interest in layered clay-based polymer nanocompositesbecause of the improved properties exhibited by the nanocomposites. Itis desirable to maximize delamination of the layered clay material intoindividual platelet particles in order to maximize some propertyimprovements, including barrier (gas permeability) improvements, and tominimize deleterious effects on some properties includingelongation-at-break. Ideally, the clay material is exfoliated intoplatelet particles with a thickness of less than about 20 nm in order toachieve clarity that is comparable to the clay-free polymer. To date,the only polymer/clay nanocomposites that meet this expectation areprepared by incorporation of organically treated clays during synthesisof the polymer from monomer. It is widely known, however, that theamount of clay that can be admixed in a polymer and still exhibitexfoliation of the layered clay is limited and some mechanicalproperties, such as elongation-at-break, are often reduced considerablyupon the addition of the clay.

Researchers recognized the value of inventing melt-compounding processesthat provide exfoliated clay composites. Namely, melt-compoundingprocesses provide more versatility of polymer choice and clay loadingand the potential for cost savings. However, with many polymer/claymixtures, the melt compounding processes explored to date do not providesufficient exfoliation of the platelet particles.

Polyesters such as poly(ethylene terephthalate) (PET) are widely used inbottles and containers which are used for carbonated beverages, fruitjuices, and certain foods. Useful polyesters have high inherentviscosity (I.V.), which allows polyesters to be formed into parisons andsubsequently molded into containers. Because of the limited barrierproperties to oxygen, carbon dioxide and the like, PET containers arenot generally used for products requiring long shelf life. For example,oxygen transmission into PET bottles which contain beer, wine andcertain food products causes these products to spoil. There have beenattempts to improve the barrier properties of PET containers by the useof multilayer structures comprising one or more barrier layers and oneor more structural layers of PET. However, multilayer structures havenot found wide use and are not suitable for use as a container for beerdue to the high cost, the large thickness of the barrier layer required,and poor adhesion of the barrier layer to the structural layer.

There are many examples in the patent literature of polymer/claynanocomposites prepared from monomers and treated clays. For example,U.S. Pat. No. 4,739,007 discloses the preparation of Nylon-6/claynanocomposites from caprolactam and alkyl ammonium-treatedmontmorillonite. U.S. Pat. No. 4,889,885 describes the polymerization ofvarious vinyl monomers such as methyl methacrylate and isoprene in thepresence of sodium montmorillonite.

Some patents describe the blending of up to 60 weight percent ofintercalated clay materials with a wide range of polymers includingpolyamides, polyesters, polyurethanes, polycarbonates, polyolefins,vinyl polymers, thermosetting resins and the like. Such high loadingswith modified clays are impractical and useless with most polymersbecause the melt viscosities of the blends increase so much that theycannot be molded.

WO 93/04117 discloses a wide range of polymers melt blended with up to60 weight percent of dispersed platelet particles. WO 93/04118 disclosesnanocomposite materials of a melt processable polymer and up to 60weight percent of a clay that is intercalated with organic onium salts.The use of clays intercalated with a mixture of onium ions is notcontemplated or disclosed.

U.S. Pat. No. 5,552,469 describes the preparation of intercalatesderived from certain clays and water soluble polymers such as polyvinylpyrrolidone, polyvinyl alcohol, and polyacrylic acid. The use of claysintercalated with organic cations is specifically excluded.

JP Kokai patent no. 9-176461 discloses polyester bottles wherein thepolyester contains unmodified sodium montmorillonite. Incorporation ofthe clay into the polyester by melt compounding is disclosed; however,the use of clays intercalated with a mixture of organic cations isneither contemplated nor disclosed.

Clays intercalated with a mixture of organic cations, typically oniumions, are used as rheology modifiers for certain coating applications;however, their use in polymer/clay nanocomposites has been neithercontemplated nor disclosed. The following references are of interestwith regard to chemically modified organoclay (clay/organic cationintercalate) materials: U.S. Pat. Nos. 4,472,538; 4,546,126; 4,676,929;4,739,007; 4,777,206; 4,810,734; 4,889,885; 4,894,411; 5,091,462;5,102,948; 5,153,062; 5,164,440; 5,164,460; 5,248,720; 5,382,650;5,385,776; 5,414,042; 5,552,469; WO Pat. Application Nos. 93/04117;93/04118; 93/11190; 94/11430; 95/06090; 95/14733; D. J. Greenland, J.Colloid Sci. 18, 647 (1963); Y. Sugahara et al., J. Ceramic Society ofJapan 100, 413 (1992); P. B. Messersmith et al., J. Polymer Sci.:Polymer Chem., 33, 1047 (1995); C. O. Oriakhi et al., J. Mater. Chem. 6,103(1996).

Therefore, as shown above, a need still exists for a polymernanocomposite comprising a clay material and articles produced therefromthat have improved barrier properties.

SUMMARY OF THE INVENTION

It has been found that clays intercalated with a mixture of organiccations, preferably onium ions, are useful for the preparation by a meltcompounding process of a polymer/clay nanocomposite with sufficientexfoliation and molecular weight for improved properties and clarity forcommercial applications, including film, bottles, and containers. Thepolymer nanocomposite of this invention is particularly useful forforming packages that have improved gas barrier properties. Containersmade from these polymer composite materials are ideally suited forprotecting consumable products, such as foodstuffs, soft drinks, andmedicines.

This invention also seeks to provide a cost-effective method forproducing barrier layers with sufficient oxygen barrier and clarity forwide spread applications as multilayer bottles and containers, includingbeer bottles.

In accordance with the purpose(s) of this invention, as embodied andbroadly described herein, this invention, in one embodiment, relates toa polymer-clay nanocomposite having an improved gas permeabilitycomprising (i) a melt-processible matrix polymer, and incorporatedtherein (ii) a layered clay material intercalated with a mixture of atleast two organic cations.

In another embodiment, this invention relates to a process for preparinga polymer-clay nanocomposite comprising (i) preparing an intercalatedlayered clay material by reacting a swellable layered clay material witha mixture of at least two organic cations, and (ii) incorporating theintercalated clay material in a matrix polymer by melt processing thematrix polymer with the intercalated clay.

In yet another embodiment, this invention relates to a process forpreparing a polymer-clay nanocomposite having an improved gaspermeability comprising the steps of: (i) preparing an intercalatedlayered clay material by reacting a swellable layered clay material witha mixture of at least two organic cations, (ii) adding the clay materialto components for forming a polymer, and (iii) conducting thepolycondensation polymerization of the components in the presence of theclay material.

Additional advantages of the invention will be set forth in part in thedetailed description, which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theadvantages of the invention will be realized and attained by means ofthe elements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory of preferred embodiments of the invention, and are notrestrictive of the invention, as claimed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be understood more readily by reference to thefollowing detailed description of the invention and the examplesprovided therein. It is to be understood that this invention is notlimited to the specific processes and conditions described, as specificprocesses and/or process conditions for processing polymer articles assuch may, of course, vary. It is also understood that the terminologyused herein is for the purpose of describing particular embodiments onlyand is not intended to be limiting.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” included pluralreferences unless the context clearly dictates otherwise.

Ranges may be expressed herein as from “about” or “approximately” oneparticular value and/or to “about” or “approximately” another particularvalue. When such a range is expressed, another embodiment includes fromthe one particular and/or to the other particular value. Similarly, whenvalues are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms anotherembodiment.

DEFINITIONS

Whenever used in this specification, the terms set forth shall have thefollowing meanings:

“Layered clay,” “layered clay material” or “clay material” shall meanany organic or inorganic material or mixtures thereof, such as asmectite clay mineral, which is in the form of a plurality of adjacent,bound layers. The layered clay comprises platelet particles and istypically swellable.

“Platelet particles,” “platelets” or “particles” shall mean individualor aggregate unbound layers of the layered clay material. These layersmay be in the form of individual platelet particles, ordered ordisordered small aggregates of platelet particles (tactoids), and smallaggregates of tactoids.

“Dispersion” or “dispersed” is a general term that refers to a varietyof levels or degrees of separation of the platelet particles. The higherlevels of dispersion include, but are not limited to, “intercalated” and“exfoliated.”

“Intercalated” or “intercalate” shall mean a layered clay material thatincludes an intercalant disposed between adjacent platelet particles ortactoids of the layered material to increase the interlayer spacingbetween the adjacent platelets and tactoids. In this invention, theintercalant is preferably a mixture of two or more different types oforganic cations.

“Exfoliate” or “exfoliated” shall mean platelets dispersed predominantlyin an individual state throughout a carrier material, such as a matrixpolymer. Typically, “exfoliated” is used to denote the highest degree ofseparation of platelet particles.

“Exfoliation” shall mean a process for forming an exfoliate from anintercalated or otherwise less dispersed state of separation.

“Nanocomposite(s)” or “nanocomposite composition(s)” shall mean apolymer or copolymer having dispersed therein a plurality of individualplatelets obtained from a layered clay material.

“Matrix polymer” shall mean a thermoplastic or melt-processible polymerin which the platelet particles are dispersed to form a nanocomposite.In this invention, however, the platelet particles are predominantlyexfoliated in the matrix polymer to form a nanocomposite.

DESCRIPTION OF THE EMBODIMENTS

The present invention relates generally to melt compounding processes toprepare polymer/clay nanocomposite compositions and to certainpolymer/clay nanocomposite compositions wherein the clay particles aretreated with a mixture of two or more organic cations, preferablyorganic cation salts. The polymer/clay nanocomposites of this inventionexhibit an unexpectedly lower gas permeability, especially oxygenpermeability, than other layered polymer/clay nanocomposites prepared bymelt compounding processes. The process of this invention may be used toprepare a wide variety of polymer/clay nanocomposite compositions.

The prior art has defined the degree of separation of platelet particlesbased on peak intensity and basal spacing value, or lack of predominantbasal spacing, as determined by X-ray analyses of polymer-plateletcomposites. Even though X-ray analysis alone often does notunambiguously predict whether or not the platelet particles areindividually dispersed in the polymer, it can often allow quantificationof the level of dispersion achieved. As such, X-ray analysis onlyprovides information related to the well-ordered aggregates, which areonly a small portion of the platelet particles present. Moreover, inpolymer nanocomposites, X-ray analysis alone does not accurately predictthe dispersion of the platelet particles in neither the polymer nor theresultant gas barrier improvement. TEM images of polymer-plateletcomposites show that platelet particles which are incorporated into atleast one polymer exist in a variety of forms, including, but notlimited to, individual platelets (the exfoliated state), disorderedagglomerates of platelets, well ordered or stacked aggregates ofplatelets (tactoids), swollen aggregates of stacked platelets(intercalated tactoids), and aggregates of tactoids.

Without being bound by any particular theory, it is believed that thedegree of improved gas barrier permeability) depends upon the embodimentratio of the resulting particle platelets and aggregates, the degree towhich they are dispersed or uniformly distributed, and the degree towhich they are ordered perpendicular to the flux of the permeant.

To obtain the improvements in gas permeability according to the presentinvention, it is preferable that the platelet particles representativeof the bulk of the composite be exfoliated, and preferably be highlyexfoliated, in the matrix polymer such that the majority, preferably atleast about 75 percent and perhaps as much as at least about 90 percentor more of the platelet particles, be dispersed in the form ofindividual platelets and aggregates having a thickness in the shortestdimension of less than about 20 nm and preferably less than about 10 nm,as estimated from TEM images. Polymer-platelet nanocomposites containingmore individual platelets and fewer aggregates, ordered or disordered,are most preferred. Significant levels of incomplete dispersion (i.e.,the presence of large agglomerates and tactoids greater than about 20nm) not only lead to an exponential reduction in the potential barrierimprovements attributable to the platelet particles, but also can leadto deleterious affects to other properties inherent to polymer resinssuch as strength, toughness, and heat resistance.

Again, without being bound by a particular theory, it is believed thatdelamination of platelet particles upon melt processing or mixing with apolymer requires favorable free energy of mixing, which hascontributions from the enthalpy of mixing and the entropy of mixing.Melt processing clay with polymers results in a negative entropy ofmixing due to the reduced number of conformations, which a polymer chainhas when it resides in the region between two layers of clay. It isbelieved that poor dispersion is obtained using melt-processiblepolyesters, for example, because the enthalpy of mixing is notsufficient to overcome the negative entropy of mixing. In contrast,generally good dispersions are obtained with polyamides due to theirhydrogen bonding character. However, the extent of this dispersion isfrequently lessened because of the negative entropy of mixing.Heretofore, efforts to achieve a favorable enthalpy of mixing ofplatelet particles with melt processible polymers by pretreating theplatelet particles (e.g., by cation exchange with alkyl ammonium ions)have been unsuccessful.

Regarding the present invention, it has been found that using clayintercalated with a mixture of organic cations while melt processingwith a polymer gives good dispersion in a resulting nanocomposite,creating mostly individual platelet particles and improving the gaspermeability of the nanocomposite. By using a mixture of organic cations(or mixed tethers), a balance of polar and non-polar groups may beachieved without conducting difficult syntheses, for example. That is,it is also easier to mix known and available cations (tethers) than todesign and synthesize new ones.

Again without being bound by any particular theory, it is believed thatgiven that a polymer chain typically comprises areas with differentcharacter (such as hydrophobicity, polarity, hydrogen bonding character,etc.), the use of a mixture of organic cations (mixed tethers) may helpthe polymer to achieve lower enthalpy of mixing by providing materialsof different polarity for interaction with different parts of thepolymer chain. To take advantage of this, the chain should havesufficient mobility and entropy to assume a conformation that isfavorable, and expanding the clay gallery and delaminating intoindividual platelet particles helps this. An additional theory is that amixture of cations (two or more tethers) might prefer to associate witha given polymer rather than with each other. The above rationalespertain primarily to the enthalpy. However, other theories areplausible.

In order to maximize the degree of exfoliation of the onium ion-treatedclays in melt polymers, it is essential to have good compatibilitybetween the matrix polymer (or oligomer, or polymer reactants) and theonium ions that are ion-exchanged at the clay platelet surface. In otherwords, the selection of the onium ions is based on the compatibility ofthe onium ions with the matrix monomers, oligomers and polymers. Withoutbeing bound by any particular theory, it is believed that the formationof the mixed onium-ion exchanged clays enhances the compatibility of thegallery, between adjacent platelets, with the matrix polymer. Also,mixed onium ions could increase the compatibility range of a nanomergallery with the matrix polymer. Mixed onium ion-intercalated clays canbe used in the PET polymerization process to prevent the collapse of theexfoliated clay particles during the polymerization of ethylene glycoland DMT in the PET synthesis process. The polarity of the matrixpolymer, e.g., PET, decreases as the degree of polymerization increases.The initial exfoliated clay in ethylene glycol may not be compatiblewith the PET matrix polymer using a single, high polarity onion ion.However, by incorporation of low polarity surfactants (onium ions) aswell as higher polarity onium ions, in the clay galleries prior toexfoliation in ethylene glycol, gallery collapse (platelet re-alignment)is avoided during polymerization of the PET.

By using the mixed onium ion-exchanged clay, one can reduce the amountof certain high molecular weight onium ions, and facilitate the particlesize reduction process (lower weight of onium ions bonded to theplatelet surfaces). For instance, ETHOQUAD 18/25, an ethoxylatedammonium ion, has a high molecular weight. For a fully ETHOQUAD18/25-exchanged Nanomer, the content of silicate in the Nanomer will beless than 50 weight percent. Also the fully onium ion-exchanged Nanomeris difficult to de-water. By using 50:50 molar ratio of the ETHOQUAD18/25:ODA (octadecylammonium), the amount of ETHOQUAD 18/25 in the finaltreated clay is reduced by 50 weight percent, the oniumion(s)-intercalated clay be can be easily de-watered, and the oniumion-intercalated clay is in a dry powder form, rather than a tackymaterial. The mixed ETHOQUAD 18/25-ODA-clay has better dispersion andexfoliation in the matrix polymer after extrusion, than that of anysingle fully treated ETHOQUAD 18/25-intercalated clay andODA-intercalated clay. The better exfoliation will be translated intobetter O₂ barrier properties.

More particularly, this invention relates to a polymer nanocompositecomprising a melt-processible polymer and up to about 25 weight percentof a swellable layered clay material which is intercalated with amixture of at least two organic cations, preferably onium ions. Theintercalated clay material has platelet particles, which are dispersedin the polymer. The polymer nanocomposite is preferably a polyesterpolymer or copolymer nanocomposite having an I.V. of at least 0.5 dL/gas measured in a mixture of 60 weight percent phenol and 40 weightpercent 1,1,2,2-tetrachloroethane at a concentration of 0.5 g/100 ml(solvent) at 25° C.

In one embodiment, the process for manufacturing the polymernanocomposite of this invention comprises (1) preparing the intercalatedlayered clay material and (2) incorporating the intercalated layeredclay material in a polymer by melt processing the polymer with theintercalated layered clay material. Melt processing includes melt andextrusion compounding. Use of extrusion compounding to mix theintercalated clay and the polymer presents two advantages. Chiefly, theextruder is able to handle the high viscosity exhibited by thenanocomposite material. In addition, in a melt mixing approach forproducing nanocomposite materials, the use of solvents can be avoided.Low molecular weight liquids can often be costly to remove from thenanocomposite resin.

The first step of this invention is the preparation of the intercalatedlayered clay material by the reaction of a swellable layered clay with amixture of organic cations, preferably ammonium compounds. The processto prepare the organoclay (intercalated clay) may be conducted in abatch, semi-batch, or continuous manner.

In another embodiment, the process of this invention comprises (i)preparing the intercalated layered clay material, (ii) adding themodified clay to a mixture of the components for forming the desiredpolymer and (iii) conducting the polycondensation polymerization in thepresence of the modified clay. The molecular weight of the polymermaterial may be increased by any of a number of known approaches or byany combination of these approaches, e.g., chain extension, reactiveextrusion, extrusion let-down, solid state polymerization or annealing,annealing under a flow of inert gas, vacuum annealing, let-down in amelt reactor, etc.

The resulting nanocomposite can then be processed into a desired barrierfilm or container with the processing procedures generally known in theart.

The nanocomposite of the present invention comprises less than about 25weight percent, preferably from about 0.5 to about 20 weight percent,more preferably from about 0.5 to about 15 weight percent, and mostpreferably from about 0.5 to about 10 weight percent of clay. The amountof platelet particles is determined by measuring the amount of silicateresidue in the ash of the polymer/platelet composition when treated inaccordance with ASTM D5630-94. Useful clay materials include natural,synthetic, and modified phyllosilicates. Illustrative of such naturalclays are smectite clays, such as montmorillonite, saponite, hectorite,mica, vermiculite, bentonite, nontronite, beidellite, volkonskoite,magadite, kenyaite, and the like. Illustrative of such synthetic claysare synthetic mica, synthetic saponite, synthetic hectorite, and thelike. Illustrative of such modified clays are fluoronatedmontmorillonite, fluoronated mica, and the like. Suitable clays areavailable from various companies including Nanocor, Inc., Southern ClayProducts, Kunimine Industries, Ltd., and Rheox.

Preferred clay materials are phyllosilicates of the 2:1 type having acation exchange capacity of 0.5 to 2.0 milliequivalents per gram ofmineral (meq/g). The most preferred clay materials are smectite clayminerals, particularly bentonite or montmorillonite, more particularlyWyoming-type sodium montmorillonite or Wyoming-type sodium bentonite.

Generally, the layered clay materials useful in this invention are anagglomeration of individual platelet particles that are closely stackedtogether like cards, in domains called tactoids. The individual plateletparticles of the clays preferably have thickness of less than about 2 nmand diameter in the range of about 10 to about 3000 nm. Preferably, theclays are dispersed in the polymer so that most of the clay materialexists as individual platelet particles, small tactoids, and smallaggregates of tactoids. Preferably, a majority of the tactoids andaggregates in the polymer/clay nanocomposites of the present inventionwill have thickness in its smallest dimension of less than about 20 nm.Polymer/clay nanocomposite compositions with the higher concentration ofindividual platelet particles and fewer tactoids or aggregates arepreferred.

Moreover, the layered clay materials are typically swellable freeflowing powders having a cation exchange capacity between about 0.3 andabout 3.0 meq/g, preferably 0.90 to 1.5 meq/g, and more preferably 0.95to 1.25 meq/g. The clay may have a wide variety of exchangeable cationspresent in the galleries between the layers of the clay, including, butnot limited to, cations comprising the alkaline metals (group IA), thealkaline earth metals (group IIA), and their mixtures. The mostpreferred cation is sodium; however, any cation or combination ofcations may be used provided that most of the cations are exchanged fororganic cations (onium ions) during the process of this invention.

Other non-clay materials having the above-described ion-exchangecapacity and size, such as chalcogens, may also be used as the source ofplatelet particles under the present invention. Chalcogens are salts ofa heavy metal and group VIA (O, S, Se, and Te). These materials areknown in the art and do not need to be described in detail here.

The organic cation mixture used to intercalate the clay material of thenanocomposite of this invention is derived from organic cation salts,preferably onium salt compounds. Organic cation salts useful for thenanocomposite and process-of this invention may generally be representedas follows:

wherein M is either nitrogen or phosphorous; X⁻ is a halide, hydroxide,or acetate anion, preferably chloride and bromide; and R₁, R₂, R₃, andR₄ are independently organic and oligomeric ligands or may be hydrogen.

Examples of useful organic ligands include, but are not limited to,linear or branched alkyl groups having 1 to 22 carbon atoms, morepreferably 1 to 12 carbon atoms, aralkyl groups which are benzyl andsubstituted benzyl moieties including fused-ring moieties having linearchains or branches of 1 to 100 carbon atoms, more preferably at leastone ligand with 12 or more carbons, in the alkyl portion of thestructure, aryl groups such as phenyl and substituted phenyl includingfused-ring aromatic substituents, beta, gamma unsaturated groups havingsix or less carbon atoms, and alkyleneoxide groups having 2 to 6 carbonatoms, more preferably 3 to 5 carbon atoms. Examples of usefuloligomeric ligands include, but are not limited to, poly(alkyleneoxide), polystyrene, polyacrylate, polycaprolactone, and the like.

Particularly useful organic cations for the organic cation mixture ofthis invention include, but are not limited to, alkyl ammonium ions,such as dodecyl ammonium, octadecyl ammonium, bis(2-hydroxyethyl)octadecyl methyl ammonium, octadecyl benzyl dimethyl ammonium,tetramethyl ammonium, and the like, and alkyl phosphonium ions such astetrabutyl phosphonium, trioctyl octadecyl phosphonium, tetraoctylphosphonium, octadecyl triphenyl phosphonium, and the like.

Illustrative examples of suitable polyalkoxylated ammonium compoundsinclude the hydrochloride salts of polyalkoxylated amines availableunder the trade name JEFFAMINE (available from Huntsman Chemical),namely, JEFFAMINE-506, which is an oligooxyethlene amine with numberaverage molecular weight of about 1100 g/mol, and JEFFAMINE 505 which isan oligooxypropylene amine with number average molecular weight of about640 g/mol, and those available under the trade name ETHOQUAD or ETHOMEEN(available from Akzo Chemie America), namely, ETHOQUAD 18/25, which isoctadecyl methyl bis(polyoxyethylene[15]) ammonium chloride, andETHOMEEN 18/25, which is octadecyl bis(polyoxyethylene[15])amine,wherein the numbers in brackets refer to the total number of ethyleneoxide units. The most preferred organic cations for use in polyesters,such as polyethylene terephthalates, are polyalkoxylated ammoniumcompounds.

Numerous methods to modify layered clays with organic cations are known,and any of these may be used in the process of this invention.

One embodiment of this invention is the modification of a layered claywith a mixture of organic cation salts by the process of dispersing alayered clay into hot water, most preferably from 50 to 80° C., addingthe organic cation salts separately or adding a mixture of the organiccation salts (neat or dissolved in water or alcohol) with agitation,then blending for a period of time sufficient for the organic cations toexchange most of the metal cations present in the galleries between thelayers of the clay material. Then, the organically modified layered claymaterial is isolated by methods known in the art including, but notlimited to, filtration, centrifugation, spray drying, and theircombinations.

It is desirable to use a sufficient amount of the organic cation saltsto permit exchange of most of the metal cations in the galleries of thelayered particle for organic cations; therefore, at least about 0.5equivalent of total organic cation salts is used and up to about 3equivalents of organic cation salts can be used. It is preferred thatabout 0.5 to 2 equivalents of organic cation salts be used, morepreferable about 1.0 to 1.5 equivalents. It is often desirable, but notrequired, to remove most of the metal cation salts and most of theexcess organic cation salts by washing and other techniques known in theart.

The particle size of the resulting organoclay is reduced in size bymethods known in the art, including, but not limited to, grinding,pulverizing, hammer milling, jet milling, and their combinations. It ispreferred that the average particle size be reduced to less than 100micron in diameter, more preferably less than 50 micron in diameter, andmost preferably less than 20 micron in diameter.

Although not preferred, the clays may be further treated for thepurposes of aiding exfoliation in the composite and/or improving thestrength of the polymer/clay interface. Any treatment that achieves theabove goals may be used.

Examples of useful treatments include intercalation with water-solubleor water-insoluble polymers, organic reagents or monomers, silanecompounds, metals or organometallics, and/or their combinations.

Treatment of the clay can be accomplished prior to the addition of apolymer to the clay material, during the dispersion of the clay with apolymer or during a subsequent melt blending or melt fabrication step.

Examples of useful pretreatment with polymers and oligomers includethose disclosed in U.S. Pat. Nos. 5,552,469 and 5,578,672, incorporatedherein by reference. Examples of useful polymers for treating the mixedorganic cation-intercalated clays include polyvinyl pyrrolidone,polyvinyl alcohol, polyethylene glycol, polytetrabydrofuran,polystyrene, polycaprolactone, certain water-dispersible polyesters,Nylon-6 and the like.

Examples of useful pretreatment with organic reagents and monomersinclude those disclosed in EP 780,340 A1, incorporated herein byreference. Examples of useful organic reagents and monomers forintercalating the swellable layered clay include dodecylpyrrolidone,caprolactone, caprolactam, ethylene carbonate, ethylene glycol,bishydroxyethyl terephthalate, dimethyl terephthalate, and the like ormixtures thereof.

Examples of useful pretreatment with silane compounds include thosetreatments disclosed in WO 93/11190, incorporated herein by reference.Examples of useful silane compounds includes(3-glycidoxypropyl)tri-methoxysilane, 2-methoxy (polyethyleneoxy)propylheptamethyl trisiloxane, octadecyl dimethyl (3-trimethoxysilylpropyl)ammonium chloride and the like.

If desired, a dispersing aid may be present during or prior to theformation of the composite by melt mixing for the purposes of aidingexfoliation of the treated or untreated swellable layered particles intothe polymer. Many such dispersing aids are known, covering a wide rangeof materials including water, alcohols, ketones, aldehydes, chlorinatedsolvents, hydrocarbon solvents, aromatic solvents, and the like orcombinations thereof.

It should be appreciated that on a total composition basis, dispersingaids and/or pretreatment compounds may account for significant amount ofthe total composition, in some cases up to about 30 weight percent.While it is preferred to use as little dispersing aid/pretreatmentcompounds as possible, the amounts of dispersing aids and/orpretreatment compounds may be as much as about 8 times the amount of theplatelet particles.

Any melt-processible polymer or oligomer may be used in this invention.Illustrative of melt-processible polymers are polyesters,polyetheresters, polyamides, polyesteramides, polyurethanes, polyimides,polyetherimides, polyureas, polyamideimides, polyphenyleneoxides,phenoxy resins, epoxy resins, polyolefins, polyacrylates, polystyrenes,polyethylene-co-vinyl alcohols (EVOH), and the like or theircombinations and blends. Although the preferred polymers are linear ornearly linear, polymers with other architectures, including branched,star, cross-linked and dendritic structures, may be used if desired.

The preferred polymers include those materials that are suitable for usein the formation of multilayer structures with polyesters, and includepolyesters, polyamides, polyethylene-co-vinyl alcohols (such as EVOH)and similar or related polymers and/or copolymers. The preferredpolyester is poly(ethylene terephthalate) (PET) or a copolymer thereof.The preferred polyamide is poly(m-xylylene adipamide).

Suitable polyesters include at least one dibasic acid and at least oneglycol. The primary dibasic acids are terephthalic, isophthalic,naphthalene-dicarboxylic, 1,4-cyclohexanedicarboxylic acid and the like.The various isomers of naphthalenedicarboxylic acid or mixtures ofisomers may be used, but the 1,4-, 1,5-, 2,6-, and 2,7-isomers arepreferred. The 1,4-cyclohexanedicarboxylic acid may be in the form ofcis, trans, or cis/trans mixtures. In addition to the acid forms, thelower alkyl esters or acid chlorides may be also be used.

The matrix polymer of this invention may be prepared from one or more ofthe following dicarboxylic acids and one or more of the followingglycols.

The dicarboxylic acid component of the polyester may optionally bemodified with up to about 50 mole percent of one or more differentdicarboxylic acids. Such additional dicarboxylic acids includedicarboxylic acids having from 6 to about 40 carbon atoms, and morepreferably dicarboxylic acids selected from aromatic dicarboxylic acidspreferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acidspreferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylicacids preferably having 8 to 12 carbon atoms. Examples of suitabledicarboxylic acids include phthalic acid, isophthalic acid, terephthalicacid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid,cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid,phenylenedi(oxyacetic acid), succinic acid, glutaric acid, adipic acid,azelaic acid, sebacic acid, and the like. Polyesters may also beprepared from two or more of the above dicarboxylic acids.

Typical glycols used in the polyester include those containing from twoto about ten carbon atoms. Preferred glycols include ethylene glycol,propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol,diethylene glycol and the like. The glycol component may optionally bemodified with up to about 50 mole percent, preferably up to about 25mole percent, and more preferably up to about 15 mole percent of one ormore different diols. Such additional diols include cycloaliphatic diolspreferably having 6 to 20 carbon atoms or aliphatic diols preferablyhaving 3 to 20 carbon atoms. Examples of such diols include: diethyleneglycol, triethylene glycol, 1,4-cyclohexane-dimethanol,propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol,3-methylpentanediol-(2,4), 2-methylpentanediol-(1,4),2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3),2,2-diethylpropane-diol-(1,3), hexanediol-(1,3),1,4-di-(2-hydroxyethoxy)-benzene,2,2b-is-(4-hydroxycyclohexyl)-propane,2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,2,2-bis-(3-hydroxyethoxyphenyl)-propane,2,2-bis-(4-hydroxypropoxyphenyl)-propane and the like. Polyesters mayalso be prepared from two or more of the above diols.

Small amounts of multifunctional polyols such as trimethylolpropane,pentaerythritol, glycerol and the like may be used, if desired. Whenusing 1,4-cyclohexanedimethanol, it may be the cis, trans or cis/transmixtures. When using phenylenedi(oxyacetic acid), it may be used as 1,2;1,3; 1,4 isomers, or mixtures thereof.

The polymer may also contain small amounts of trifunctional ortetrafunctional comonomers to provide controlled branching in thepolymers. Such comonomers include trimellitic anhydride,trimethylolpropane, pyromellitic dianhydride, pentaerythritol,trimellitic acid, trimellitic acid, pyromellitic acid and otherpolyester forming polyacids or polyols generally known in the art.Suitable polyamides include partially aromatic polyamides, aliphaticpolyamides, wholly aromatic polyamides and/or mixtures thereof. By“partially aromatic polyamide,” it is meant that the amide linkage ofthe partially aromatic polyamide contains at least one aromatic ring anda nonaromatic species. Suitable polyamides have an article formingmolecular weight and preferably an I.V. of greater than 0.4.

Preferred wholly aromatic polyamides comprise in the molecule chain atleast 70 mole % of structural units derived from m-xylylene diamine or axylylene diamine mixture comprising m-xylylene diamine and up to 30% ofp-xylylene diamine and an aliphatic dicarboxylic acid having 6 to 10carbon atoms, which are further described in Japanese PatentPublications No. 1156/75, No. 5751/75, No. 5735/75 and No. 10196/75 andJapanese Patent Application Laid-Open Specification No. JP 95529697.

Polyamides formed from isophthalic acid, terephthalic acid,cyclohexanedicarboxylic acid, meta- or para-xylylene diamine, 1,3- or1,4-cyclohexane(bis)methylamine, aliphatic diacids with 6 to 12 carbonatoms, aliphatic amino acids or lactams with 6 to 12 carbon atoms,aliphatic diamines with 4 to 12 carbon atoms, and other generally knownpolyamide forming diacids and diamines can be used. The low molecularweight polyamides may also contain small amounts of trifunctional ortetrafunctional comonomers such as trimellitic anhydride, pyromelliticdianhydride, or other polyamide forming polyacids and polyamines knownin the art.

Preferred partially aromatic polyamides include, but are not limited topoly(m-xylylene adipamide), poly(m-xylyleneadipamide-co-isophthalamide), poly(hexamethylene isophthalamide),poly(hexamethylene isophthalamide-co-terephthalamide),poly(hexamethylene adipamide-co-isophthalamide), poly(hexamethyleneadiparnide-co-terephthalamide), poly(hexamethyleneisophthalamide-co-terephthalamide) and the like or mixtures thereof.More preferred partially aromatic polyamides include, but are notlimited to poly(m-xylylene adipamide), poly(hexamethyleneisophthalamide-co-terephthalamide), poly(m-xylyleneadipamide-co-isophthalamide), and/or mixtures thereof. The mostpreferred partially aromatic polyamide is poly(m-xylylene adipamide).

Preferred aliphatic polyamides include, but are not limited topoly(hexamethylene adipamide) and poly(caprolactam). The most preferredaliphatic polyamide is poly(hexamethylene adipamide). Partially aromaticpolyamides are preferred over the aliphatic polyamides where goodthermal properties are crucial.

Preferred aliphatic polyamides include, but are not limited topolycapramide (nylon 6), poly-aminoheptanoic acid (nylon 7),poly-aminonanoic acid (nylon 9), polyundecane-amide (nylon 11),polyaurylactam (nylon 12), poly(ethylene-adipamide) (nylon 2,6),poly(tetramethylene-adipamide) (nylon 4,6),poly(hexamethylene-adipamide) (nylon 6,6),poly(hexamethylene-sebacamide) (nylon 6,10),poly(hexamethylene-dodecamide) (nylon 6,12),poly(octamethylene-adipamide) (nylon 8,6), poly(decamethylene-adipamide)(nylon 10,6), poly(dodecamethylene-adipamide) (nylon 12,6) andpoly(dodecamethylene-sebacamide) (nylon 12,8).

The most preferred polyamides include poly(m-xylylene adipamide),polycapramide (nylon 6) and poly(hexamethylene-adipamide) (nylon 6,6).Poly(m-xylylene adipamide) is a preferred polyamide due to itsavailability, high barrier, and processability.

The polyamides are generally prepared by processes which are well knownin the art.

Although not necessarily preferred, the polymers of the presentinvention may also include additives normally used in polymers.Illustrative of such additives known in the art are colorants, pigments,carbon black, glass fibers, fillers, impact modifiers, antioxidants,stabilizers, flame retardants, reheat aids, crystallization aids,acetaldehyde reducing compounds, recycling release aids, oxygenscavengers, plasticizers, nucleators, mold release agents,compatibilizers, and the like, or their combinations.

All of these additives and many others and their use are known in theart and do not require extensive discussion. Therefore, only a limitednumber will be referred to, it being understood that any of thesecompounds can be used in any combination so long as they do not hinderthe present invention from accomplishing its objects.

This invention also relates to articles prepared from the nanocompositematerial of this invention, including, but not limited to film, sheet,pipes, tubes, profiles, molded articles, preforms, stretch blow moldedfilms and containers, injection blow molded containers, extrusion blowmolded films and containers, thermoformed articles and the like. Thecontainers are preferably bottles.

The bottles and containers of this invention provide increased shelfstorage life for contents, including beverages and food that aresensitive to the permeation of gases. Articles, more preferablycontainers, of the present invention display a gas transmission orpermeability rate (oxygen, carbon dioxide, water vapor) at least 10%lower (depending on clay concentration) than that of similar containersmade from clay-free polymer, resulting in correspondingly longer productshelf life provided by the container. Desirable values for the sidewallmodulus and tensile strength may also be maintained.

The articles may also be multilayered. Preferably, the multilayeredarticles have a nanocomposite material disposed intermediate to otherlayers, although the nanocomposite may also be one layer of atwo-layered article. In embodiments where the nanocomposite and itscomponents are approved for food contact, the nanocomposite may form thefood contact layer of the desired articles. In other embodiments it ispreferred that the nanocomposite be in a layer other than the foodcontact layer.

The multilayer articles may also contain one or more layers of thenanocomposite composition of this invention and one or more layers of astructural polymer. A wide variety of structural polymers may be used.Illustrative of structural polymers are polyesters, polyetheresters,polyamides, polyesteramides, polyurethanes, polyimides, polyetherimides,polyureas, polyamideimides, polyphenyleneoxides, phenoxy resins, epoxyresins, polyolefins, polyacrylates, polystyrene, polyethylene-co-vinylalcohols (EVOH), and the like or their combinations and blends. Thepreferred structural polymers are polyesters, such as polyethyleneterephthalate and its copolymers.

In another embodiment of this invention, the polymer-clay nanocompositeand the molded article or extruded sheet may be formed at the same timeby co-injection molding or co-extruding.

Another embodiment of this invention is the combined use of silicatelayers uniformly dispersed in the matrix of a high barrier thermoplastictogether with the multilayer approach to packaging materials. By using alayered clay to decrease the gas permeability in the high barrier layer,the amount of this material that is needed to generate a specificbarrier level in the end application is greatly reduced. Since the highbarrier material is often the most expensive component in multilayerpackaging, a reduction in the amount of this material used can be quitebeneficial. With the nanocomposite layer being sandwiched between twoouter polymer layers, the surface roughness is often considerably lessthan for a monolayer nanocomposite material. Thus, with a multilayerapproach, the level of haze is reduced.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a more complete disclosure and description of howthe resin compositions claimed herein are made and evaluated. They arenot intended to limit the scope of what the inventors regard as theirinvention. Efforts have been made to insure accuracy with respect tonumbers (e.g., amounts, temperature, etc.) but some errors anddeviations should be accounted for. Unless indicated otherwise, partsare by weight, temperature is in ^(B)C or is at room temperature andpressure is at or near atmospheric.

Examples 1-3 and Comparative Example 1

30 grams of a refined Wyoming-type sodium montmorillonite with cationexchange capacity of about 0.95 meq/g available from Southern ClayProducts was added to 1.0 L of hot (about 85^(B)C) distilled water thenstirred for about 2 minutes in a Henschel high-speed multi-blade mixerwith a heater attached to maintain the temperature at about 85^(B)Cwhile mixing. An aqueous solution of 28.5 meq of hydrochloric acid and28.5 meq of amine from mixtures (shown as Examples 1-3) of JEFFAMINE-506(EOA) and JEFFAMINE-505 (POA) as listed in Table 1 was added to theHenschel mixer and blended for about 2 minutes.

Comparative Example 1, also listed in Table 1, also utilizes the sameprocess described above and below except that only JEFFAMINE-506 (EOA)was used as an intercalant.

A white precipitate formed almost immediately after the addition of theammonium salt to the clay slurry. The white precipitate was separated byuse of a Beckman Model J-6B Centrifuge, washed with a 50:50 v/v mixtureof distilled water and isopropanol with mixing in the Henschel mixer,filtered, then dried at 60^(B)C for at least 24 hours. The particle sizeof the dried clay was reduced to about 10-15 micron using a hammer milland then a jet mill. The WAXS basal spacing and silicate content (ash)were determined for the clay product as listed in Table 1.

TABLE 1 Tether Basal Mole Grams Ash of Spacing of Ratio of GramsIntercalated Intercalated Examples EOA/POA EOA of POA Clay (wt %) Clay(nm) Comparative 100/0  32.06 0 73.4 1.40 Example 1 1 75/25 21.88 4.5672.4 1.38 2 50/50 15.01 9.12 72.1 1.38 3 25/75 7.50 13.68 72.9 1.42

4.3 grams of the ammonium-intercalated clay was dry mixed with 395.7grams PET 9921 (commercially available from Eastman Chemical Company),which is a polyethylene terephthalate containing about 3.5 mole percentof 1,4-cyclohexanedimethanol and having I.V. of about 0.72 dL/g. The drymixture was dried in a vacuum oven overnight at 120^(B)C. then extrudedat a temperature of about 275^(B)C. on a Leistritz Micro 18 mm twinscrew extruder using general purpose screws with a RPM of 200. Theextrudate was cooled on an air belt and then pelletized as it exited thedie.

Films were prepared by compression molding using a Pasadena hydraulicpress with an applied pressure of about 3000 lbs. at a temperature of280° C. with a molding time of about 1.15 minutes. To prevent stickingof the material to the molding plates, Teflon coated aluminum foil wasused. To achieve a target thickness, a 10-mil thick shim was used. Themolded films were immediately quenched in ice water to obtain anamorphous sample, thereby eliminating the effect of crystallinity on themeasured gas permeability. The permeability results of the films arepresented in Table 2, including the control (neat PET 9921, availablefrom Eastman Chemical Company) and the comparative example, which doesnot utilize a mixture of organic cations.

TABLE 2 Tether Mole Ratio Ash Oxygen Permeability Examples EOA/POA (wt%) (cc-mil/100 in²-day-atm) Comparative 100/0  3.14 8.0 Example 1 175/25 2.73 7.4 2 50/50 2.95 6.6 3 25/75 2.89 7.8 PET 9921 Control n/a 010.2

Table 2 shows that clays treated with the mixture of ammonium ionsprovides polyester nanocomposites with significantly improved oxygenpermeability compared to unmodified PET (PET 9221 control). Theunmodified PET does not contain any platelet particles. Moreover, theunmodified PET does not contain platelet particles treated with amixture of onium ions according to the present invention.

In addition, and even more particularly surprising, the results of Table2 illustrate that treating clay (used in a polymer nanocomposite) with amixture of different types of ammonium ions (EOA/POA) improves oxygenpermeability compared to clay treated with just one ammonium ion (EOA).

A comparison of Examples 1 and 3, for example, shows that a clay treatedwith a 50/50 ratio of a mixture of ammonium ions (EOA/POA) has an oxygenpermeability of 6.6 cc-mil/100 in²-day-atm while a clay treated with oneammonium ion (100/0 of EOA/POA) has an oxygen permeability of 8.0cc-mil/100 in²-day-atm. This result is particularly surprising in thatboth clays have been treated with an ammonium ion; however, the claytreated with the ammonium ion mixture provides unexpectedly improvedresults.

Comparisons of Examples 1 and 2 (75% EOA/25% POA) and Examples 1 and 4(25% EOA/75% POA) also indicate improved barrier properties of filmsmade from nanocomposites treated with mixtures of organic cations over afilm prepared from a nanocomposite treated with only one organic cation.

The following examples further illustrate the formation of mixed oniumion treated clays.

ETHOQUAD 18/25-ODA clay system:

100 g of purified sodium montmorillonite (Na-CWC) with cation exchangecapacity of 1.4 meq/g available from Nanocor, Inc. was added to 4.0 L ofhot (85° C.) distilled water to form a clay slurry and the clay slurrywas stirred by a paddle mixer until all clay solids were dispersed. Themixed onium ion solutions were prepared by mixing an ETHOQUAD18/25-water solution and ODA in a 1:1 molar ratio in HCL solution. Themixed onium ion solution was added to the clay slurry. A clayprecipitate formed immediately upon mixing. The total mixture was mixedand maintained at 85° C. for about 2 hours. The water was removed byfiltration. The obtained precipitate was washed twice before drying inan oven at 120° C. The dried clay was ground with a mechanical grinder,and further ground by jet-mill or air-classifier-mill to reduce theparticle size to about 10 to 15 microns. Finally, the ground sampleswere analyzed by powder X-ray diffraction. The following tables 3 and 4summarize the composition and basal spacing of the mixed ETHOQUAD18/25-ODA treated clays with different molar ratios of ETHOQUAD 18/25and ODA.

TABLE 3 Example E-18/25:ODA Ash of clay (wt %) D₀₀₁ of Treated Clay 5100:0  41.2 36.0 6 75:25 46.0 34.0 7 50:50 52.0 31.0 8 25:75 60.0 27.0 9 0:100 72.0 22.0

Q182-Q142 system:

Q182 and Q142 are quaternary ammonium surfactants available from TomahProducts, Inc. Q182 has a straight C₁₈ chain, while Q142 has a straightC₁₁ chain and ether linkage with a C₃ chain linked to the nitrogen atom.The combination of different chain length and polarity surfactants willcreate a multiple onium ion-intercalated clay which has bettercompatibility with the matrix polymer, particularly when the matrixpolymer undergoes polymerization or further polymerization while incontact with the intercalated and/or exfoliated intercalates containinga plurality of ion-exchanged onium ions of different polarity. Thecombination of different chain length and polarity onium ions willcreate an intercalated clay which has a better compatibility range for ahost of matrix polymers, while preventing re-alignment and collapse(will provide better dispersibility) of exfoliated clay platelets. Thebasal spacing data of the single onium ion-exchanged Q142 or Q182 oniumions alone, and mixed onium ion-exchanged Q142/Q 182-clays are shownbelow in Table 3 as Examples 10, 11 and 12.

TABLE 4 Q142/Q182 Example (molar) Ash of Clay (wt %) D₀₀₁ of TreatedClay 10 100:0  72.7 20.2 11 50:50 69.4 25.1 12  0:100 64.2 28.0

Throughout this application, various publications are referenced. Thedisclosures of these publications in their entireties are herebyincorporated by reference into this application in order to more fullydescribe the state of the art to which this invention pertains.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention. Otherembodiments of the invention will be apparent to those skilled in theart from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

What is claimed is:
 1. An intercalate comprising a layered clay materialintercalated with a mixture of at least two organic cations and amelt-processible polymer, said two organic cations intercalated into thelayered clay material in a molar ratio in the range of 25:75 to 75:25.2. The intercalate of claim 1, wherein the melt-processible polymer is apolyester, polyetherester, polyamide, polyesteramide, polyurethane,polyimide, polyetherimide, polyurea, polyamideimide, polyphenyleneoxide,phenoxy resin, epoxy resin, polyolefin, polyacrylate, polystyrene,polyethylene-co-vinyl alcohol, copolymer thereof, or a mixture thereof.3. The intercalate of claim 1, wherein the melt-processible polymer is apolyester, polyamide, polyethylene-co-vinyl alcohol, a copolymerthereof, or a mixture thereof.
 4. The intercalate of claim 1, whereinthe melt-processible polymer is poly(m-xylylene adipamide), EVOH, acopolymer thereof, or a mixture thereof.
 5. The intercalate of claim 1,wherein the melt-processible polymer is poly(ethylene terephthalate) ora copolymer thereof.
 6. The intercalate of claim 1, comprising about 5%to about 85% weight percent of the melt-processible polymer intercalatedbetween adjacent layers of the layered material.
 7. The intercalate ofclaim 1, comprising from about 15 to about 70 weight percent of thepolymer intercalated between adjacent layers of the layered material,based on the total weight of the intercalate.
 8. The intercalate ofclaim 1, comprising from about 30 to about 50 weight percent of thepolymer intercalated between adjacent layers of the layered material. 9.The intercalate of claim 1, wherein the layered clay material is anatural, synthetic or modified phyllosilicate.
 10. The intercalate ofclaim 1, wherein the layered clay material is montmorillonite, saponite,hectorite, mica, vermiculite, bentonite, nontronite, beidellite,volkonskoite, saponite, magadite, kenyaite, or a mixture thereof. 11.The intercalate of claim 1, wherein the clay material comprises asmectite clay.
 12. The intercalate of claim 1, wherein the clay materialis a free flowing powder having a cation exchange capacity from about0.9 to about 1.5 meq/g and is selected from the group consisting of asodium montmorillonite; sodium bentonite; calcium montmorillonite;calcium bentonite; and mixtures thereof.
 13. The intercalate of claim 1,exfoliated such that at least 50 percent of the layered clay material isdispersed in the form of individual platelet particles and tactoidshaving a thickness of less than or equal to 60 nm.
 14. The exfoliatedintercalate of claim 13, wherein the tactoids have a thickness of lessthan about 30 nm.
 15. The intercalated of claim 1, wherein the organiccations are derived from onium salt compounds.
 16. The intercalate ofclaim 15, wherein the onium salt compounds comprise ammonium orphosphonium salt compounds.
 17. The intercalate of claim 1, wherein themixture of organic cations are alkyl ammonium ions, alkyl phosphoniumions, or polyalkoxylated ammonium ions.
 18. The intercalate of claim 17,wherein the alkyl ammonium ions are dodecyl ammonium, octadecylammonium, bis(2-hydroxyethyl) octadecyl methyl ammonium, octadecylbenzyl dimethyl ammonium, or tetramethyl ammonium.
 19. The intercalateof claim 17, wherein the alkyl phosphonium ions are tetrabutylphosphonium, trioctyl octadecyl phosphonium, tetraoctyl phosphonium, oroctadecyl triphenyl phosphonium.
 20. The intercalate of claim 17,wherein the organic cations are mixture of polyalkoxylated ammonium ionsand the polyalkoxylated ammonium ions derived from a hydrochloride saltof oligooxyethylene amine, a hydrochloride salt of oligooxypropyleneamine, octadecyl methyl bis(polyoxyethylene[15]) ammonium chloride, oroctadecyl bis(polyoxyethylene[15])amine, wherein the numbers in bracketsare the total number of ethylene oxide units.
 21. The intercalate ofclaim 20, wherein the hydrochloride salt of oligooxyethylene amine has anumber average molecular weight of about 1100 g/mol, and thehydrochloride salt of oligooxypropylene amine has a number averagemolecular weight of about 640 g/mol.
 22. The intercalate of claim 1,wherein the melt-processible polymer comprises poly(ethyleneterephthalate) or a copolymer thereof, the layered clay materialselected from the group consisting of montmorillonite and bentonite, andthe mixture of at least two organic cations comprises a hydrochloridesalt of oligooxyethylene amine with a number average molecular weight inthe range of about 200-5,000 g/mol and a hydrochloride salt ofoligooxypropylene amine with a number average molecular weight of about640 g/mol.
 23. An exfoliate formed by shearing the intercalate of claim1 to form a plurality of delaminated clay layers and clay tactoids. 24.A process for preparing a polymer-clay intercalate comprising the stepsof: (i) preparing an intercalated layer clay material by reacting aswellable layered clay material with a mixture of at least two organiccations, said two organic cations intercalated with the swellablelayered clay material in a molar ratio of 25:75 to 75:25, and (ii)intercalating a matrix polymer between adjacent layers of saidintercalated clay material by melt processing the matrix polymer withthe intercalated clay.
 25. The process of claim 24, wherein step (ii) isconducted by a batch mixing or a melt compounding extrusion process. 26.A polymer-clay intercalate made by the process of claim
 24. 27. Apolymer-clay exfoliate made by shearing the intercalate made by step (a)in the process of claim
 24. 28. A process for preparing a polymer-clayintercalate comprising the steps of: (i) preparing an intercalatedlayered clay material by intercalating a swellable layered clay materialwith at least two organic cations, (ii) adding the clay material topolymerizable polymer components for forming a polymer, and (iii)conducting a polycondensation polymerization of the polymer componentsin the presence of the clay material to intercalate the polymer betweenadjacent layers of the layered clay material.
 29. A polymer-clayintercalate made by the process of claim
 28. 30. A polymer-clayexfoliate made by shearing the intercalate made by the process of claim28.